Relay and jammer selection schemes for improving physical layer security in two-way cooperative networks

This paper is concerned with the relay and jammers selection in two-way cooperative networks to improve their physical layer security. Three different categories of selection schemes are proposed which are; selection schemes without jamming, selection schemes with conventional jamming and selection schemes with controlled jamming. The selection process is analyzed for two different network models; single eavesdropper model and multiple cooperating and non-cooperating eavesdroppers’ model. The proposed schemes select three intermediate nodes during two communication phases and use the Decode-and-Forward (DF) strategy to assist the sources to deliver their data to the corresponding destinations. The performance of the proposed schemes is analyzed in terms of ergodic secrecy rate and secrecy outage probability metrics. The obtained results show that the selection schemes with jamming outperform the schemes without jamming when the intermediate nodes are distributed dispersedly between sources and eavesdropper nodes. However, when the intermediate nodes cluster gets close to one of the sources, they are not superior any more due to the strong interference on the destination nodes. Therefore, a hybrid scheme which switches between selection schemes with jamming and schemes without jamming is introduced to overcome the negative effects of interference. Finally, a comparison between relay and jammers selection schemes in both one-way and two-way cooperative networks is given in terms of both secrecy metrics. The obtained results reveal that, despite the presence of cooperating eavesdroppers, the proposed selection schemes are still able to improve both the secrecy rate and the secrecy outage probability of the two-way cooperative networks.